The long-range objective of this project is to develop new antibiotics to treat infections with multi-antibiotic-resistant (MAR) Gram+ bacteria, especially Staphylococcus aureus and Enterococcus fecalis. We have targeted the replication-specific Gram+DNA polymerase III (pol III) and selective pol III inhibitors of the 6-anilinopyrimidine class as platforms for design of the drugs. In phase I we both established the validity of pol III as a target and synthesized lead drugs that protect mice from lethal Staph. aureus infection. The research plan for Phase II combines: (i) continued evaluation of lead drug candidates, 3-(4-hydroxybutyl) derivatives of 6-(3-ethyl-4- methylanilino) uracil (HB-EMAU) and 6-(3-iodo-4-methylanilino)uracil (HB-IMAU) for efficacy and toxicity in mice; (ii) synthesis of new derivatives with hydrophilic 3-substituents and with substituted 6-anilino and 6-benzylamino groups to obtain more potent antibacterial compounds; (iii) synthesis of prodrugs of active compounds that will have enhanced solubility and oral bioavailability. Compounds with potent pol III and antibacterial activity in vitro will be tested for ability to protect mice from lethal Staph. Aureus infections. Active compounds will be subjected to pharmacokinetic analysis in mice, and suitable compounds will be tested in a thigh model of Staph. aureus proliferation in mice. Active compounds will be tested further in the thigh model for efficacy against E. fecalis and MAR organisms to evaluate the spectrum of antibiotic activity. Preclinical studies of lead drug candidate(s) will be undertaken by Microbiotix Inc. A major pharmaceutical company will be recruited as a development. Health relatedness. There is a crisis in the management of diseases caused by MAR strains of Gram+ bacteria. This work will result in the development of new antibiotic drugs acting on a novel target, and is both technologically innovative and highly relevant to human health. PROPOSED COMMERCIAL APPLICATIONS: The drug industry is aggressively seeking to develop novel antibiotics to attack novel targets. The agents which we propose not only strike a novel target; they are covered by an existing composition of matter patient. Agents emerging from this work should have excellent potential for commercial development.